Navigation Bar: Ability to enable on every device 1/2

This adds a new Menu item Settings -> System -> Navigation Bar

Patch Set 5 : Just a rebase
Patch Set 6: Rebase
Patch Set 8: Rebase
Patch Set 9: Rebase

Change-Id: I23a508fa3268e63fbbc9a8305d011db3ca7722a0
Realtime change of Nav Bar Height

Conflicts:

	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
Change in Nav Bar Width in landscape - 1/2